System of distribution



April 10, 1928.

D. c. PRINCE Inventor" 1 David C. Prince,

2% His Attorney.

Patented Apr. 10, 1928.

UNITED STATES PATENT orFicE.

DAVID C. PRINCE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYSTEM OF DISTRIBUTION.

Application filed September 23, 1924'. Serial No. 739,443.

My present invention relates to systems of electrical distribution, and more particularly to systems in which electrical energy of one form is received and converted to elec- 5 trical energy of another form.

The object of my invention is to provide a means for regulating the voltage ina system ot-the class mentioned in such a way that the voltage at which the converted energy is supplied to a consumption circuit may be maintained substantially constant over' wide variations in the load.

My invention is applicable both to systems for converting direct current to alternating current and systems for converting alternating'current to direct current. I

.The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims;

my invention itself,-however, both as to its organization and method of operation "will best be understood by'referenc'eto-the following description taken in connection with the accompanying drawing in which Fig. 1 shows diagrammatically a circuit arrangement which maybe 'used incarrying my invention'into effect in 'a system for converting alternating current" to"d;ire'ct current, and Figl'2 is a diagrammatic representation of a circuit arrangementin which my invention is applied to a system for converting direct current to alternating.

In the arrangement shown in Fig. 1, I have indicated three-phase alternating current supply'conductors 1, 2 and 3 which supply current to the delta connected primary windings 4 of a transformer. Current is supplied from the primary windings 4 to the double Y-connected windings 5 and 6. The neutral points of the windings 5, 6 are connected throu h the windings 7, 8 of an interphase trans ormer to the negative side 9 of a direct current consumption circuit. The other terminals of windings 5, 6 are all connected to a series of rectifying valves 10. which in the present instance are indicated as of the thermionic type, but which may be any type of rectifier desired. The cathods of all of these valves or rectifiers are connected in parallel and supplied with heating current by means of the transformer 11, which receives current from the sup-ply conductors 2, 3.v The positive termina1'12 of the direct current distribution circuit is connected to the central point of secondary 11.

A wave analysis of various rectifier connections shows that the effect of an interphase transformer is always to eliminate the same harmonics as are eliminated by the corresponding number of phases without the interphase transformer: The average direct current "component, however, is different. For any polyphase combination the average direct current-component is greater without the interphase transformer.

I propose to make use of 'thls phenomenon in order to maintain substantially constant the output voltage supplied over a wide range of load. This result may be brought about in various ways. In the arrangement shown in Fig. 1, the interphase transformer is provided with a third' leg 13, having an air gap 14:- This third leg is wound with a saturating winding 15, which is excited by the generator 16 -through'a resistance 17. An increase in the current supplied to the load circuit would normally be accompanied by a' drop in voltage at the terminals 9 and 12. However, such an increase in direct current would cause a unidirectional flux to pass through the third leg 13 ofthe interphase transformersaturating the transformer, and to all practical purposeseliminating thefeflect of the interphase transformer from the system and causing it to operate as a straig'ht six-phase rectifier inwill rise. With thecombination shown in Fig. 1, the rise in the direct current voltage produced'by change from double three-phase to straight six-phase'operation is proportional'to the ratio of .995-to .827. This inherent voltage rise does not take place instantly, but is progressive between the point where the interphase transformer is fully effective and the point where its effect is entirely eliminated.

When the load taken is light and the direct current voltage up to its maximum, the resistance 17 is short circuited by the contact 18 being held up by the coil 19. As soon as the voltage starts to fall the coil 19 releases contact 18 and the resistance 17 is then included in the saturation current circuit. The current in the saturating coil 15 is such that lit e e h P ge of the unidire ti l flux from winding 7 and 8 through the middle leg of the interphase transformer. The reduction in the current through coil 15 stead of a double three-phase rectifier." As a result, the average, direct current voltage caused by. the opening of contact, 1S therefore, permits an increase in the, saturating flux which in turn produces an increa s e in the )j tt ptli voltage, 13 suitable design of 1 thesatiiration transformer a nd tliie 7 and 8 the desired regulating effect'inay he obtained without the use o. an extra sou1 ce, of saturating current i Similar arrnngcnmn ts my be used with a. triple single-phase rectifier or a quarterphase. rectifier. 1n the case of the triplesinglephaise reetificrthe increase in voltage due to saturatiouof the interphase transformer is in the ratio of .995-to .637; In the caseot-the quarter-phaserectifier the ratio of-voltage increase is .900 to .637.

InFi'g. 2,1 have, indicated the application o fjmny inv.entioii ,t.o a system. for conyerting direct current to alternating. In this case, direct curren is supplied fromthe conduit. tors, 20, 21 tel-h two fi-mmiectedsets: of primary. windings 22,-and 23. Current isfsup; plied fronrthe positive line through the windings 24 and 25 of an interphase trans; former, and the findings 22and 23 areconnected :to, the, anodes of a series of valvesQG of thermionic three-electrodetype, al-tho othertypes of valves for controlling the How i current to wind ngs 22 nd. 23 'm y. be employed.- if esiregli The onda y-W nd- 1g$ fil -D13 uta t-t th l at g rentdis ribu i o i mains28- T Wind g, 29 nr h mi dle... jg f: he nt tp ase rans.- erme i sup-pl e th at rat ng cu en y e 211239 3 whi alsopp i saturat ringrcurnent to awinding 32 Qnthemiddle eg. of h eterphase. ra sfon n r th gri u rcut f a ves. 6- xcitat en tor theigr s is btai d "baraci g aw ntl gr 34,and ..31i1 the grid, circuits ininduetive relation to the windings 22 and 2 3 respec t r y he nL 2rP esenfitwm r n th plate circuits is provided with. the air. gap as indieated in order that it shall have normally a, fairly high exciting .current so hi! fi dS e y tem n ion as though the interphase transformer, Omitt d W l nde earie oads e e e of the ntciphase; st rme i s intov p t im, aarljt yst ma a rr sp n i ly h gher iihe i n utpi tv t e- In dir tiqrr to t iis inhcrerrt efiect current is sup; plied to the saturating windingQQ-in such ewes thatibq e: 0ft i at thm a rindin fifitz n no ma trassis s ntsat l i gfi beflwf When h Ou p "Qltege s 9% t ea ted at 33 11 2 2 a the saturating current. Tlle eflegtfift l 'llgis to a t emanatesiQ e efi r t iet at .911 a: h -z rp ase arma it or ean iiiea $i'hiahe e P-utvfl a a e two r ts-e eeiime i when 1 3 i aer ate to -m ethen-fi e Sa e S M Q a e of h e fiie. "T

At the 1 same time that the plate circuit- ,ses

eliginges troiu threeto. si x -ph as e operation the. grid circuit must, r'nake a sim1lar l eg htflo ads the gr d"ciirre riti terids to he larger than' at heai y loads. This larger grid current. tends to saturate the interphase transformer" through the third leg of the interplrase t ;an,sfiornrer, core. This renders the interphase transformer ineflective and makes the lrids operate six phase inst as the plates are doing. At the, same time, if; -1I1 .l.DQ -:Qa 6 in voltagecleses the contact 33 & ,d.-in.qreases the current, in the-saturation inding this Current will saturate, the, gridinterphase transtorrne z. This change is .als o ini the. direction converting; the, gride irc it into; ,a t ght i -these, circuit to wntonmth the change u ng..- 0. ghfi ab ut ihelpl r r circuit; j

What I claim. s ew nd-ds mte s mt 2 by Letters Patent of the, .Un i ted Sta te is 1:4 Thezcombiiiationfin a Sy tem Q velectrical distr but on 01? a' urr nt l ll an a ternating cement. c rcuit connected to one .of-said cirenits S9urce of current connected to -tljg oth erheirciiit, means interc naecti a aid circu tsiqqngpiqim mg; a pairiofmin g on a; i geme fi o e means. m apn mg w ea e -cent; u ent a fi aintain. a -pxal temiaedr ear eotr agnetiq at rates lla d 2? i'nra s. operable ta reg l e t aqsat it an-fi a d m re; in. espeiisate weet e-tee lt ge. fi tdndire t urreat sirciet? he mbina ha n sys ewq ele tri al i tri ution- 2th; d ne c irr nti i aJJdz' an a t rnating sunse it-ea aoas HELQQQQd-W-Wfi Qifi aisi rw ts a ds in oi cu rent meanes -s51 t e r 9? ear-it means ietfi wmiaet ag ,3 5, lPCQlQiCQWPPS ing a pair of on a inagn tic core, a third wyirrdi onsard core, 111eignsfo1ys1111- vty a 9 t ir afl i T a re dermimtlsat rating. ri nt, am i ai ar-iable to regulate the, current',of..said third winding in aebordgngewith the Vol agel of said direct eurrent cireuit. Y

3. The combination a system ofelcc trical distribution a direct current circuitand an alternating, current circuit a load res l d; P0 1 'imt l ti i tt and a anta of curr nt? 'c yected to the other circuit means "mt erconneet ngrsaid; eircuitsfcompns ing a .pa iii .ot.lnfincliiigs magnetic core, a blH Alli- 1. tth- 9! em ires; e t wi aa p edeter- Inlne saturating. Current, the" saturating current rus p al iect being ,so chosen that h cur entupp 1e i ei ead ;a, -J i conjuncgon therpyithj fto produce I a; preden ta' t' i H in; l a l9l 015 21}? a e i t 1 mi mt m i a 131 an.- sent.- hgxvmage; i th QZ d Ci'IiCEl- F: yer vilidej iaila inthe.lo CII T GDQIQ d. Slip;-

III!

ind

plemental means responsive to variations in voltage in the load circuit for varying the current supplied to the third Winding and thereby assisting in maintaining constant the voltage of the load circuit.

4. The combination in a system of electrical distribution of a direct current circuit and an alternating current circuit, a load connected to one of said circuits and a source of current connected to the other circuit, means interconnecting said circuits comprising a pair of windings on a magnetic core, a third winding on said core, a source of current connected to said third winding through means comprising an impedance device, and means 0 erable to control the connections of said evice in accordance with the voltage of said direct current circuit.

5. The combination in a system of electrical distribution of a direct current circuit and an alternatin current circuit, a load connected to one 0 said circuits and a source of current connected to the other circuit, means interconnecting said circuits comprising a pair of windings on a magnetic core, a third Winding on said core, means for supplying to said third winding a predetermined saturating current, and means responsive to variations in voltage in the load circuit for varying the current supplied to the third winding and producing thereby such variation in the saturation of the core as to maintain substantially constant the voltage of the load circuit over a wide range in the load current.

6. The combination in a system of electrical distribution of a direct current circuit and an alternating current circuit, a load connected to one of said circuits and a source of current connected to the other circuit, means interconnecting said circuits compris ing a pair of windings on a magnetic core, said windings being connected individually to two separate sets of windings associated with the alternating current circuit, and means independent of the current supplied to the load for producing a predetermined degree of saturation of the magnetic core, said last mentioned means being arranged to act in conjunction with the current supplied to the load to maintain substantially constant the voltage of the load circuit over a wide range in the load current.

7. The combination in a system of electrical distribution of a direct current circuit and an alternating current circuit, a load connected to one of said circuits and a source of current connected to the other circuit, means interconnecting said circuits comprising a pair of windings on a magnetic core,

said windings being connected individually to two separate sets of windings associated with the alternating current circuit, a third winding on said core and means for supplying to said third winding a predetermined saturating current, the saturating current thus supplied being so chosen that the current supplied to the load will act in conjunction therewith to produce a predetermined variation of the saturation of the core which will maintain substantially constant the voltage of the load circuit over a wide range in the load current.

8. The combination in a system of elec trical distribution of a direct current circuit and an alternating current circuit, a load connected to one of said circuits and a source of current connected to the other circuit, means interconnecting said circuits comprising a pair of windings on a mag netic core, said windings being connected individually to two separate sets of windings associated with the alternating current circuit, said core and the windings thereon being so constructed and proportioned that the saturation of the core varies with the load current in such a way that the voltage of the load circuit is maintained substantially constant while the load current varies in value.

9. The combination of polyphase windings, a direct current circuit, an interphase transformer comprising a magnetic core and windings wound on said core and connected between said direct current circuit and said polyphase windings, and means operable in accordance with the voltage of said direct current circuit for varying the saturation of said core to regulate the relation between the voltages of said polyphase windings and said direct current circuit.

10. The combination of polyphase windings, a direct current circuit, an interphase transformer comprisin a magnetic core and windings wound on said core and connected between one side of said direct current circuit and said polyphase windings, means connected between said polyphase windings and the other side of said direct current circuit for rectifying the current transmitted between said polyphase windings and said direct current circuit, and means operable in accordance with the voltage of said direct current circuit for varying the saturation of said core to regulate the relation between the voltages of said polyphase windings and said direct current circuit.

In witness whereof, I have hereunto set my hand this 22nd day of September, 1924.

DAVID C. PRINCE. 

